title: 1-(4-Hy-droxy-phen-yl)-2-(2-oxidonaphthalen-1-yl)diazen-1-ium methanol hemisolvate.
abstract: In the title compound, C16H12N2O2·0.5CH3OH, the H atom of the -OH group has been transfered to the N atom in the azo group, forming a zwitterion. Hence, there is an intra-molecular N-H⋯O, rather than an O-H⋯N, hydrogen bond in the mol-ecule. The mol-ecule is almost planar, the dihedral angle between the benzene ring and the mean plane of the naphthalene ring system being 4.51 (6)°. In the crystal, mol-ecules are linked to and bridged by O-H⋯O hydrogen bonds involving the methanol mol-ecule, which is located about a twofold rotation axis, and hence half-occupied, forming zigzag chains along [001]. Mol-ecules are also linked via C-H⋯π and π-π inter-actions, the latter involving adjacent benzene and naphthalene rings and having a centroid-centroid distance of 3.6616 (13) Å, forming a three-dimensional network.
authors.affiliation: Unité de Recherche de Chimie de l'Environnement et Moléculaire Structurale, (CHEMS), Faculté des Sciences Exactes, Département de Chimie, Université Constantine 1, 25000 Constantine, Algeria.
authors.forename: Mohamed Amine
authors.initials: MA
authors.lastname: Benaouida
authors.forename: Souheyla
authors.initials: S
authors.lastname: Chetioui
authors.forename: Salah Eddine
authors.initials: SE
authors.lastname: Bouaoud